I'll ask this here, since it seems to be the local repository of BIAB knowledge, and I haven't been able to find anything. I'm getting ready to do my first BIAB batch soon and was wondering, what ratio of water to grain do most people use for BIAB? 1.0-2.0 qt / lb is of course the recommended range for AG brewing, but it sounds like most people who aren't sparging are using a much thinner mash than this?
I ask because I would think (just from MichaelisMenten kinetics) that efficiency would be reduced at extreme thinness (unless mashing for much longer), since the substrate concentration is reduced (and so the rate of conversion is reduced).
Use as much water as you can so that you end up with about 5.5 gallon when you're finished boiling. I use about 2.6 quarts/pound of grain. But every system is different. I crush my grains twice, mash for 90 minutes, stir and reheat half way through, mash out at 170 deg, and drain for about a half hour and consistently get 72% efficiency.